The functionality of many computing systems and other devices relies on effective display of information using a display. More recently, the display has also been used in an interactive manner as a direct user input device. For instance, a display might be equipped with touch sensitive resistive and/or capacitive arrays to detect a portion of the display screen being physically contacted.
Some conventional interactive displays use “vision capture” technology in which a camera is positioned behind the display screen, the display screen composed of one or more layers of transparent or semitransparent material. An infrared illuminator is also positioned behind the display screen to illuminate an object in front of or in contact with the display. Illumination light (i.e., light originating from the illuminator) reflected from the object is received by the camera, which takes a picture of the reflected light. The picture is used as an electronic input to the system. Since the placement, size, and brightness of the object in front of the display influences its image taken by the camera, the object may be used to input information into the system.
Some of the illumination light is reflected not off the object, but off of the relatively flat surfaces of the transparent or semi-transparent layer(s) forming the display screen. The result is that the camera will see a specular reflection of relatively strong brightness at a specific area of the display screen. The specular reflection may be so strong that it would be difficult to distinguish any image actually reflected from an input object within the area of the specular reflection. The specular reflection may even saturate the camera in that specific area. The effect is somewhat analogous to the situation in which a person looks downward at a shallow pond on a sunny day. The person might be able to view the bottom of the pond except for the area that is at or close to the sun's blinding reflection.
Accordingly, specular reflections can adversely impact the ability to use an interactive display as input, especially if the input object is positioned at an area of the display screen in which the camera is experiencing a specular reflection.